The topic of immigration is on everyone’s front burner these days, for often very sad reasons. For many, the interest, or the threat, of immigration comes from the effects any group of immigrants at any time have had on what one considers the dominant American culture. It has always been this way, sadly, whether it is disquiet over the Irish, the Chinese, the Eastern European Jews, the Italians or Polish, the Cubans, or the Vietnamese boat people, to name just a few.

Still, there is another aspect to being (as we are, whether we admit it or not) a nation of immigrants: the difference between those who have by practice or generation, regardless of how much they honor their original culture, become Americanized, and those who carry the original culture because it is still theirs. It is this which is explored in Mfoniso Udofia’s “Her Portmanteau,” now receiving its west coast premiere at Boston Court Pasadena. Here three steps on that assimilation scale look at what is shared, and what separates a “foreigner” from a part of our American ethnocultural tossed salad.

Iniabasi Ekpeyong has just arrived from Nigeria. Though born in the US she has been raised by her late father back on the family compound. Now she is in New York to meet the mother and half sister she hasn’t laid eyes on since childhood. Her mother Abasiama Ufot, and her half-sister Adiaha Ufot are unfamiliar in more ways than one might expect, as language and culture and a disorienting distance between expectation and reality create barriers and end-run openings for the three women.

This work is part of Udofia’s 9-part cycle of plays documenting the Ufot family, but stands well on its own. In it, the entire idea of the US as a paradise is placed up against the friction between traditional family roles and hierarchies, traditional modes of hospitality, even traditional and adapted foods, and how such things can hamper even well-intentioned attempts at understanding. What one runs from and what one runs toward become the ways in which these people balance the bonds of blood and the differences of experience, like a portmanteau, an old fashioned style of suitcase built with two distinct sides one fills separately and then brings together to fasten. Only then do they touch.

Dele Ogundiran is Iniabasi, expecting reunion traditions unfamiliar here, and anxious in many directions at the end of an interminable flight. Watching her severity and fear gradually unbend gives weight and humanity to the awkwardness of difference where one expects to find sameness. Omoze Idehenre, as the American-raised daughter Adiaha, brings to the obligatory balance of inherited traditions and American-centered cultural frameworks a sense of exasperation and kindness which lay the groundwork the play develops. Joyce Guy gives the mother of the two other women, Abasiama, a palpable aura of apology, for distance and for difference, gradually laying out her own burdens, and gradually absorbing those her daughters face.

Director Gregg T. Daniel gives this word-rich play a sense of activity and interwoven characters which keeps it from devolving into a kind of panel discussion. This is particularly important as significant sections of the piece are at least partially in Ibibio, one of Nigeria’s traditional languages which is spoken here laced with occasional English words and phrases. That Iniabasi speaks it as first language, her mother Abasiama can return to it willingly, but – though she understands it well enough – Adiaha chooses to only use English is shorthand for the transitions which are at the core of the play. Daniel makes this work.

A note of praise also for Tesshi Nakagawa’s set design for the cramped Inwood apartment in NYC, for Jeff Gardner’s subtle but essential sound design, and for Erin Walley’s props, so evocative of the cultural interplay so necessary in telling this tale.

Yes, unless you speak Ibibio, you will not understand every word. That is, one assumes, a point – a rich conversation and interaction which is in itself isolating here, though communal somewhere else. Take that in, as part of “Her Portmanteau”: part of what these characters carry with them as they bump into being American.